Launch Pad

Evidence shows these 3 steps are crucial to stop virus spread


See the AOA coronavirus/COVID-19: Crisis Response page for resources.

A new study underscores the effectiveness of personal protective equipment along with physical distancing in preventing COVID-19's spread.

The study's researchers, several associated with McMaster University in Hamilton, Ontario, investigated the effects of physical distancing, face masks and eye protection on virus transmission in health care and non-health-care settings. They looked at evidence in 172 observational studies across 16 countries and six continents, with no randomized, controlled trials and 44 relevant comparative studies in health-care and non-health-care settings. The studies, which included research on coronavirus, severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), covered about 25,700 patients.

Their study findings were published online June 1 in The Lancet. The study concludes that while no protection is full-proof these measures were effective in preventing spread.

  • Transmission of viruses was lower with physical distancing of one meter or more, compared with a distance of less than one meter (equivalent to about 3 feet, 3 inches); protection was increased with additional distance.
  • Face mask use could result in a large reduction in risk of infection with stronger associations with N95 or similar respirators compared with disposable surgical masks or similar.
  • Eye protection (such as goggles and face shields) also was associated with less infection.

"With no effective pharmacological interventions or vaccine available in the imminent future, reducing the rate of infection (i.e., flattening the curve) is a priority, and prevention of infection is the best approach to achieve this aim," write the study's authors noting that further research is needed.

The study was released, just as a new Gallup poll says Americans are continuing to observe social or physical distancing. Yet, they increasingly are opting to gather in small groups of friends and family. In April, 84% of Americans were avoiding those gatherings. From that peak, that figure had dipped to 56% in recent polling.

Andrew Morgenstern, O.D., director of the AOA's Clinical Resources Group, says this is no time to let up on these interventions, because the evidence indicates that distancing, masks and eye protection work in preventing the spread.

Dr. Morgenstern notes that the findings were consistent with Centers for Disease Control and Prevention and AOA guidance on protective measures. Researchers did study distancing at about three feet and determined it prevented spread but noted that the more distance (the commonly cited 6 feet in the U.S., for example) the more effective infection control.

He also points out the limited number of studies on COVID-19. In the midst of the pandemic, data is still being gathered.

For instance, the Food and Drug Administration (FDA) reissued June 7 its emergency use authorizations on the types of respirators that can be decontaminated for reuse by health care providers. The FDA news release referred to some N95 respirators made in China, which may vary in design and performance.

"As doctors of optometry, we are on the front lines of public health," Dr. Morgenstern says. "As such, the responsibility for preventing the transmission of diseases starts with us in our practices."

June 15, 2020

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